Nuclear sclerosis in dogs can look a bit concerning until you know what is going on. Thankfully, this age-related discoloration to the lens of the eye won’t significantly affect your dog’s ability to see. Integrative veterinarian Dr. Julie Buzby explains this condition and compares it to cataracts in dogs—the condition dog parents most often confuse with nuclear sclerosis.
Picture a set of reading glasses perching on your senior dog’s muzzle. Pretty adorable, right?
While dogs don’t need reading glasses as they age like humans do, they do undergo an age-related change in their eyes called nuclear sclerosis. This common medical condition in dogs causes discoloration to the center of the eye, and in some cases, may make it a bit harder for dogs to see things that are close to them.
Thankfully, dogs don’t need to use their close-up vision for reading like humans do, so dogs don’t need reading glasses. In fact, most dogs don’t seem phased by nuclear sclerosis at all. However, you may wonder: Is my dog’s eye discoloration normal? Can my dog see ok? Is it cataracts? This article answers these questions, and hopefully puts your mind at ease about nuclear sclerosis in dogs.
The anatomy of the eye
In order to understand what might be happening in your dog’s eyes, it helps to know some eye anatomy. When light first enters the eye, it passes through the cornea, or clear portion of the front of the eye. Then it travels through the fluid-filled anterior chamber of the eye and passes through the pupil. The pupil is the opening in the iris (i.e. colored portion of the eye). It can dilate or constrict to regulate how much light gets through.
Next, the light passes through the posterior chamber of the eye to the lens. This hard, disc-like structure is responsible for focusing the beam of light. To do this, it must be able to change shape (stretch or condense slightly) in a process called accommodation. In a normal dog, the lens is clear and is comprised of fibers that renew over time.
The light then travels through the jelly-like vitreous humor before hitting the retina. Photoreceptors contained in the retina take the light and transform it into a nerve signal. This signal then travels down the optic nerve to the brain where it is perceived as an image. If any part of this process breaks down, the appearance of the eye can change and/or vision may be compromised.
What is nuclear sclerosis in dogs?
Nuclear sclerosis is also known as lenticular sclerosis. It isn’t clear how nuclear sclerosis occurs. However, most veterinary ophthalmologists think that as new fibers develop around the outside of the lens, it compresses the older fibers in the center (i.e. nucleus) of the lens. This makes the nucleus more dense. Its name, nuclear sclerosis, describes this process well. Sclerosis refers to abnormal hardening of a tissue, which in this case is the nucleus of the lens.
As a result of these changes, a small, round, pearly grey-colored opacity forms in the center of the lens. You may also notice a blue or grey haziness when looking into your dog’s eyes. Sometimes, this is easier to observe when looking at an affected eye from the side.
Which dogs are most commonly affected?
Nuclear sclerosis generally occurs in middle aged or older dogs—typically those over the age of seven. It doesn’t seem to be more common in any particular breeds. However, increased exposure to UV radiation (typically as sunlight) may make nuclear sclerosis occur more rapidly.
How is nuclear sclerosis in dogs diagnosed?
When the veterinarian examines your dog’s eyes, he or she will use a light to visualize the lens and see if the light appears to be passing through the lens and to the back of the eye. This can help distinguish between nuclear sclerosis and cataracts, an opacity of the lens that we will discuss in a bit.
If the lens has a grey or milky color in the center and is clear around the edges with no true areas of opacity, this fits with nuclear sclerosis. Additionally, the vet will look for a yellow-green glow created by light bouncing off a reflective structure in the back of the dog’s eye called the tapetum.
This structure is responsible for the green glow of an animal’s eyes when light hits them in the dark. If the vet sees a tapetal reflection, he or she knows light is getting through the lens and to the back of the eye. Then it can be sensed by the retina and turned into an image by the brain.
Does nuclear sclerosis cause blindness in dogs?
Even though there is an observable change to the lens, nuclear sclerosis does not significantly affect vision. Most dogs are able to see just fine. Occasionally, some dog parents describe seeing signs of far-sightedness, almost as if their dog needs reading glasses. Affected dogs may also struggle with depth perception. This may make it harder for them to navigate stairs or catch a treat flying through the air.
What is the treatment for nuclear sclerosis in dogs?
Dogs with nuclear sclerosis do not require any treatment. There are no specific medications or supplements that will reverse the changes you are seeing. It is a normal part of the aging process. The good news is it does not lead to any other eye diseases or significantly affect vision.
Now that we have discussed nuclear sclerosis, let’s move on to a brief discussion of cataracts. When I diagnose a dog with nuclear sclerosis, my clients are often understandably relieved. Many of them saw the hazy lens and understandably assumed the worst—that their dog had a cataract.
Nuclear sclerosis vs cataracts in dogs
Both of these conditions affect the lens. Nuclear sclerosis involves greyish compressed lens fibers whereas cataracts are white opacities of the lens that form due to lens fiber degeneration. Initially, a cataract may form at the center of the lens. This is the same place as nuclear sclerosis. However, a cataract may eventually encompass the entire lens while nuclear sclerosis typically stays confined to the center.
Cataracts can significantly affect a dog’s vision. Some dogs with cataracts will become blind because light can’t get through the opaque lens to the retina. Unlike nuclear sclerosis, cataracts can also cause other eye health issues such as uveitis (i.e. inflammation of the iris and other structures) and glaucoma (i.e. increased pressure in the eye). Cataracts are not considered a normal consequence of aging. They have a variety of causes including:
- Endocrine disease like diabetes mellitus
- Nutritional deficiencies
- Trauma to the eye
How are cataracts treated?
Dogs who are mostly or completely blind due to cataracts but have a normally functioning retina may benefit greatly from cataract surgery. A veterinarian who has been board certified by the American College of Veterinary Ophthalmology will perform the procedure while your dog is under general anesthesia. The veterinarian will break up and then remove the diseased lens in a process known as phacoemulsification. Then the veterinary ophthalmologist will implant an artificial lens to restore your dog’s vision.
Unfortunately, there are no other effective treatment options for cataracts. The good news, though, is that cataract surgery can greatly improve a dog’s quality of life. Dog parents often report that their dog is joyfully running around like a puppy again after the surgery. Understandably, dog parents may wonder, “Is my dog too old for anesthesia?” or “Is my dog too old for surgery?” Thus, it is always a good idea to discuss the pros and cons of surgery with your veterinarian and veterinary ophthalmologist.
For a variety of reasons, cataract surgery may not be possible for every dog. The good news is, many blind dogs also live happy, fulfilled lives. One of the ways you can help your visually impaired pup is to apply our signature product, Dr. Buzby’s ToeGrips® dog nail grips.
Added traction can help visually impaired dogs
As dogs begin to lose their vision, they may become more tentative when moving from place to place, especially in an unfamiliar location. Many dog parents over the years have told me how much more confidently their blind dogs would walk when wearing ToeGrips. That added bit of traction can be a big confidence boost!
Hope for dogs with nuclear sclerosis (and cataracts)
If you suspect something might be going on with your dog’s eyes, make an appointment with your veterinarian. Early detection of eye problems generally gives the best outcomes. If it turns out your dog has nuclear sclerosis—great! This is good news because it is a normal aging change and unlikely to have any major effects on your dog’s vision.
If you dog is diagnosed with cataracts instead, this can be a harder diagnosis to come to terms with. However, finding the cataract sooner allows you and your vet to proactively watch for any complications. It also gives you a chance to start planning now for how to help your dog adjust as his or her vision changes. Plus, cataract surgery may be able to restore your dog’s vision. And even if it isn’t an option, blind dogs can have many wonderful years ahead of them.
Does your dog have nuclear sclerosis?
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